Cathode-ray tube provided with at least one clamping band



Jan. 20, 1970 w. F. NIENHUIS ET AL I 3,490,636

GATHODE-RAY TUBE PROVIDED WITH AT LEAST ONE CLAMPING BAND Filed May 22, 1968 .FIG.2

INVENTOR5 WILLEM F-NIENHUIS HENDRIK BONGENAAR Adi/ United States Patent US. Cl. 2'20 2.1 3 Claims ABSTRACT OF THE DISCLOSURE A cathode ray tube having a rectangular picture window which adjoins a conical portion and forms a juncture therewith which is surrounded by a clamping band. The corners of the window are provided with thickened shoulder portions having a surface the generatrices of which extend substantially parallel to the tube axis. These shoulders are provided with grooves which extend parallel to the tube axis. An adhesive is provided between the clamping band and the tube envelope which also fills the grooves thus securely fastening the clamping band to the envelope.

The invention relates to a cathode-ray tube having a substantially rectangular picture window part, the protruding edge of which is provided with at least one clamping band which is secured to the glass of the bulb by means of an adhesive. The invention particularly relates to a television display tube in which a part of the upstanding side-wall-portion of the window part located between the picture surface and the clamping band is uncovered at least in part.

In order to protect cathode-ray tubes from implosion, it is known to arrange one or more metal clamping bands around the tube at the area of its maximum cross-section. In order to prevent such bands from sliding off the smooth glass surface and to increase the safety to implosion, an adhesive is introduced into the space between the glasswall and the band, generally after the clamping bands have been tensioned. This is especially the case if an intermediate band is provided between the bulb and the clamping band. Since, however, the clamping band mainly presses on the corners of the side-wall of the window, no adhesive can be provided at these corners between thte band and the glass-wall because the band closely joins the glass. Due to the fact that at the corners the band and the glass do not adhere to each other, the degree of safety to implosion can be adversely affected.

According to the invention, this disadvantage is avoided by externally providing the corners of the window with thickened shoulders having grooves which extend parallel to the tube axis and which are filled with an adhesive.

The shoulders have a surface the generatrices of which extend substantially parallel to the tube axis so that they do not tend to slide off this surface. Due to the fact that the grooves are filled =with adhesives, the band and the glass adhere sufiiciently to each other at these areas to ensure a satisfactory safety to implosion.

One or more, as the case may be annular, intermediate bands may be provided between the clamping band and the glass surface. However, in order to ensure that the "Ice front of the tube slightly projects beyond the cabinet of the apparatus, the part of the upright sidewall of the window located between the clamping band and the picture surface may be left entirely or partially uncovered.

The invention will now be described more fully with reference to the drawing, in which:

FIGURE 1 is a perspective view of a cathode-ray tube according to the invention, and

FIGURE 2 is a sectional view of a corner part of such a tube.

Referring now to FIGURE 1, reference numeral 1 denotes the window, reference numeral 2 the cone and reference numeral 3 the neck of a television display cathoderay tube. The upstanding side-wall 4 of the window 1 is provided at the corners with thickened shoulders 5 having grooves 6. The surfaces of the shoulders have generatrices which extend substantially parallel to the tube axis. A clamping band 8 is arranged around the side-wall 4, while the grooves 6 and the space remaining between the clamping band 8 and the bulb wall 4 are filled with an adhesive 7, for example, a suitable synthetic resin such as polyester or epoxy resin.

Since the band 8 exerts a strong pressure on the shoulders 5, the adhesive can be provided :at the corners only in the grooves 6. Due to the presence of these grooves, the clamping band 8 thus adheres also at the corners sufiiciently to the glass to obtain a satisfactory safety to implosion.

In FIGURE 2, a metal intermediate band 9 is disposed between the clamping band 8 and the bulb Wall 4, which intermediate band may have a larger width than the clamping band 8. A portion of the glass-wall between the picture surface 1, the clamping band 8 and the annular intermediate band 9 remains uncovered so that the front of the bulb can protrude beyond the cabinet of the apparatus. If desired, however, the intermediate band may extend as far as the picture surface of the window. This intermediate band may be an annular band or may consist of two or more parts. It has been found that the adhesive need be provided only between the glass and the inner metal hand because in the case of FIGURE 2, the frictional contact between the steel clamping band 8 and the intermediate band 9 is suflicient to prevent sliding off.

It is known from US. Patent 3,071,280 to provide the outer wall of a bulb of a cathode-ray tube with ribs, but in this case no clamping band was used. The sole object of the ribs was therefore to prevent the occurrence of scratches and other external damages on the straight sides of the rectangular window. At the corner, the ribs were omitted because due to their stronger curvature, these corners are relatively considerably stronger than the straight sides.

What is claimed is:

1. A cathode-ray tube comprising an evacuated envelope having longitudinal axis with a substantially rectangular picture window part of one end thereof adjoining a conical portion and forming a juncture therewith, a metal clamping band surrounding said juncture, the comers of said juncture being externally provided with thickened shoulders having a surface the generatrices of which extend su-bstantialy parallel to said axis and having grooves which extend substantially parallel to said axis, and an adhesive between said clamping band and said envelope and filling the grooves.

2. A cathode-ray tube as claimed in claim 1, in which at least one intermediate band is arranged between the clamping band and said juncture.

, 3 4 3. A cathode-ray tube as claimed in claim 1 in which FOREIGN PATENTS the part ofthe juncture located between the clamping 66 band and the display surface is uncovered at least in part. 4/1966 France References Cited MARTHA L. RICE, Primary Examiner 5 UNITED STATES PATENTS US 3,314,566 4/1967 Minneman et a1. 

